A team of researchers from Cornell Engineering has developed novel polymer-based substrates for packaging micro-scale electronic sensors that completely vaporize when triggered with remote radio frequency (RF) signals. The team uses ultra low-power Microelectromechanical systems (MEMS) actuators and rubidium heat sources for making the sensors disappear in an extremely controllable way.

The Cornell researchers include Professor Amit Lal, Ved Gund Ph.D. ’17 and Alex Ruyack, from the SonicMEMS Laboratory within the School of Electrical and Computer Engineering, and Professor Chris Ober, Katherine Camera Ph.D. ’16 and Amanda Leonardi from the Ober Group within the Department of Materials Science and Engineering.

Data gathered by micro-scale sensors can revolutionize our understanding of both natural and man-made environments. By integrating these micro-scale with advanced circuits and electronics (which consume very low power and possess wireless transmission capabilities), it is possible to monitor environmental conditions. These sensors can be connected in a local network, or used with the emerging internet-of-things (IoT) platform. Experts estimate that 30 billion objects including but not limited to devices, homes, computers, and even human beings will be part of the giant network that forms the IoT, enabling embedded electronics, hardware, software and sensors to interface with the physical world.

For devices with a short useful lifetime of sensors on the scale of weeks to months, the effort in deploying and then recovering them can be prohibitive. Tracking and recovering each micro-scale device individually, especially in a large-area network is nearly impossible and can potentially contaminate the environment. Another concern is the potential that adversaries could acquire the devices and reverse engineer the electronics or steal the data, leading to loss of valuable information. One approach to solve the problem of data security and environmental contamination is physically eliminating the sensors by making them vanish with a remote trigger while leaving behind no physical trace. This is what the Cornell team has demonstrated.

At the heart of the project developed by the Cornell team are MEMS single shot valves that are 100% reliable in triggering and vaporize the thermally-degradable polymer substrates using embedded rubidium heat sources. The power-consumption of the valves is more than 100 times lower than the previous best reports from literature, making them extremely attractive for this application. The substrate is stable under ordinary conditions but vaporizes at 180 degrees C, leaving behind little to no residue upon heating and therefore leaving behind no available signature of their existence. Integrating chemical etch sources that decompose and release hydrofluoric acid, etches the electronics and enables the substrate to fully vaporize.

The electronics have been developed in collaboration with Honeywell and the Defense Advanced Research Projects Agency (DARPA) funded the project.